Gas-Particle Partitioning of Vehicle Emitted Primary Organic Aerosol Measured in a Traffic Tunnel

We
measured the gas-particle partitioning of vehicle emitted primary
organic aerosol (POA) in a traffic tunnel with three independent methods:
artifact corrected bare-quartz filters, thermodenuder (TD) measurements,
and thermal-desorption gas-chromatography mass-spectrometry (TD-GC-MS).
Results from all methods consistently show that vehicle emitted POA
measured in the traffic tunnel is semivolatile under a wide range
of fleet compositions and ambient conditions. We compared the gas-particle
partitioning of POA measured in both tunnel and dynamometer studies
and found that volatility distributions measured in the traffic tunnel
are similar to volatility distributions measured in the dynamometer
studies, and predict similar gas-particle partitioning in the TD.
These results suggest that the POA volatility distribution measured
in the dynamometer studies can be applied to describe gas-particle
partitioning of ambient POA emissions. The POA volatility distribution
measured in the tunnel does not have significant diurnal or seasonal
variations, which indicate that a single volatility distribution is
adequate to describe the gas-particle partitioning of vehicle emitted
POA in the urban environment.